drm/i915/cdclk: Plumb the full atomic state deeper

drm/i915/cdclk: Plumb the full atomic state deeper

Various parts of the cdclk code need access the full atomic
state. Currently it's being dug out via the cdclk_state->base.state
pointer, which is not great as that pointer isn't always valid.
Instead plumb the full atomic state from the top so that it's
clear that it is in fact valid.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240528184945.24083-1-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>